Spark plug



D. M. HUTCHINSON.

SPARK PLUG.

APPLICATION flLED APR. I6, 1921- Patented July 18, 1922.-

I I/ 1 1 Il /l 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1/ 1 11111/ 1 1 1 1 1 1111 1 1 1 1 1 1 1 1111111111111/1 1 1 1 111/1 1 1 1 1 1 1 11 1 111 11 1111 1 1 1 1 1 1111 11 1 1 1 1 1 1 1 1 1/ 1 1 1 1 1 1 1 1 1 1 1 1 11 1 1 1 1 11111 1 1 1 1 H 1 1 1 1 1 1 1 1 1 1 M1 1 1 1 11 1/ 1 /1/11 1 1 1 1 1 1 1 1H 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 I I 1 STATES DAVID M. HUTGHINSON, or ST. LOUIS, MissoUnI.

SPARK PLUG.

ins 13,219.

Specification ofLetters Patent.

Patented July 18. 192 2.

Application filed Apri1 16,,1921 Serial No. 461,748.

To all whom it may concern:

Be it known that I, DAVID M. HUTGHIN- soN, a citizen of the United States, and resident of the city of St. Louis and State of Missouri, have invented certain new and useful Improvements in Spark Plugs, or which the following is a specification containing'a' full, clear, and exact description. reference being had to the accompanying drawings, forming a part hereof.

My invention relates to improvements in spark plugs and has for its primaryobject a spark plug having a spark gap formedin the porcelain insulator. Said spark gap being located near the bottom of the porcey lain so that very little of the increased intensity of the electric current is lost by the resistance of the conductor below the gap. A further object is to construct a spark plug and a spark gap located near the lower extremity of the porcelain insulator, and which the electrode is formed of two wires, each wire being headed and said heads being placed apart to form a spark gap and two portions of the central electrode being secured together in such a manner that the electrode can be handled as if it were constructed of one piece.

In the drawings, Fig. 1 is a cross sectional view of the spark plug embodying my invention.

Fig. 2 is a fragmental view of the central electrode with parts broken away and in section, showing the manner of securingthe two sections of the electrode together for assembling.

In the construction of my device I employ a spark plug having a screw threaded shell 3. This screw threaded shell is provided,

with a wrench engaging surface 4, and a. pair of central bores 5 and 6. The bore 6 being screw threaded to receive the lock nut 7. The bore 6 is made larger than the-bore 5 so that the shoulder 8 is formed and on the shoulder is placed the washer 9. Resting on this washer is the enlargement 10 which is formed integrally with the porcelain insulator 11. Resting on top of the enlargement 10 is a washer 12 against which the lower end of the lock nut 7 bears. This lock nuttogether with the washers 8 and 12 prevent leakage of compression. Secured in the shell 3 is an electrode 13 which extends toward the center of the bore or opening 5. Formed centrally in the porcelain insulator 11 are bores 14 and 15. The bore 15 being concentric with but of less diameter than the bore 14, so that the shoulder 16 will be formed. This shoulder16 is formed as near as possible to the lower-end of the insulator 11 without impairing its strength. Secured in the bore 15 is a headed electrode'lf. This head 18 being slightly smaller than the bore 14 but suflicientlv large to rest on the shoulder 16. Located in the bore 14 is an electrode 19 having ahead 20. This head being of the same diameter as the head 18. Interposed between the heads 18 and 20 is "a washer '21 having a central opening 22. i The washer 21 is made of any suitable heat resistance non-conducting material and. is of the same size as the heads 18 and 20. The opening 22'forms a spark chamber and the washer 21 is of the proper thickness to give the required spacing of the :heads so that perfect spark gap will'be formedand one that does not require adjustment after the electrodes have been inserted in place. Sur

rounding the heads 18 and 20 and washer 21. is a sleeve 23. This sleeve is also formed of non-conducting material and is preferably made so that the heads 18 and 20 and washer 21 will have to be forcedtherein. This sleeve then holds the electrodes 17 and 19 together with the washer 21, so that the same may be readily inserted in the bores 14 and 15. This sleeve also prevents any cement from coming in between the heads 18 and 20. and washer 21 which might cause them to be spaced. farther apart "than the thickness of the washer and destroy the spark gap by making a space too great for the electrode current to jump across.

While I have shown my device with the electrode 19 extending above the top of the porcelain and into the cap 24' which is crimped to the topof the porcelain, I do not desire'to limit myself to this precise construction as I may make the electrode 19 heavy enough to be screw threaded on the'upper end'and receive the binding nut 25 in place of the structure shown without departing from the spirit of my invention. I am also aware that spark plugs have been and consequently a great deal of the energy gained by the gap is again absorbed by the electrode below the gap. In my. device it is my intention to make the electrode below 2 nezae e the gap as short aspossible and thus lessen the absorption of the increased energy imparted by the gap. I

While I have shown the sleeve 23 as crimping over the heads 18 and 20, I may also construct a sleeve in the "form of a 1101 low cylinder whose length will be equal to the thickness of the heads 18 and 20 and washer 21.

Having fully described my invention, what I claim is: a j

1. In a spark plug a one piece insulator having concentric bores extending therethrough, and a shoulder adjacent the lower end thereof, a relatively long upper electrode having ahead on, its lowerend, seated in onerot said bores,and a relatively short lower electrode having a head formed, on

its upper end, seated insaid bore and ex tending through the other bore, an insulat ing washerprovided withan opening, positioned between said heads, a sleeve embracing said heads and said insulating Washer for holding the two electrodes in assembled position before inserting in said bores.

2. In aspark plug aone piece insulator provided with concentric bores a relatively short lower electrode having a head on its vupper end, said head :being' seatedin one of said bores and the'body otthe electrode ex tending through the other bore and beyond the lower end of the insulator, a relatively long upper electrode having ahead formed on its lowerend, seated insaidbore, an insulating disc having a hole fornied there through positioned between said heads so as to form a spark gap adjacent the lower 7 end of the insulator, a sleeve embracing said heads and said insulating disc for holding the electrodes in assembled form before inserting in the insulator and also acting as a shield to prevent cement passing between the heads and insulating disc, said sleeve being crimped over the said heads.

3. In a spark plug a one piece insulator provided with an upper andlower bore concentrically arranged and of, different. diameters, the upper bore; of considerably greater :length than the lowerbore, an electrode provided with ahead on: its extreme lower end seated in theupper bore, a relatively short electrode'provided with a head on its extreme upper end seated in the lower bore,.an insulating disc provided with an opening seated in the upper bore between saidheads, so as to for na spark gap near the point where the lower electrode emerges from the insulator, thereby lessening the re sistance and absorption of electrical energy between the spark gapand, firing gap, and a sleeve snugly embracingthe insulating disc and heads of said electrodes for hold .ing the electrodes inassernbled position before inserting in saidbores. p p

In testimony whereot, I have signedmy name to thisspeeification,

i DAVID nUrcrnNsoN, 

